Idle air bypass

ABSTRACT

A valve assembly of novel configuration is associated with the main air induction passage of a fuel-injected, spark-ignited, automotive internal combustion engine for the purpose of regulating the idle air flow. The valve assembly has an inlet connected upstream of the throttle and an outlet connected downstream of the throttle. A pintle controls the restriction that the valve assembly imposes on the idle air flow. The valve assembly is controlled by the engine computer selectively energizing a solenoid on the assembly. In one embodiment the solenoid armature controls flow through another flow path of the valve assembly that parallels the idle air flow path. A movable internal wall divides the valve assembly&#39;s body into two variable volume chambers. One chamber forms part of the idle air bypass while the other forms part of the parallel flow path. The one chamber is essentially at manifold vacuum while the other is regulated by a bleed valve and two orifices in the parallel flow path. Positioning of the movable wall positions the pintle. In a second embodiment, one chamber is communicated with the idle air flow path by an orifice, and the other is communicated with the idle air flow path by constructing the pintle from a hollow tube containing the two orifices and placing the bleed valve external to the tube for direct action with one of the orifices.

REFERENCE TO A RELATED APPLICATION

This application is a continuation-in-part of Ser. No. 07/463,093, filedJan. 10, 1990 now U.S. Pat. No. 4,989,564.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to an idle air bypass valve for a fuel injectedinternal combustion engine.

Such a valve is used in an automotive vehicle to control the flow ofcombustion air into the engine when the engine is idling. Because theload on the engine may vary for any of a number of different reasonswhile the engine is idling, the idle air bypass valve is required sothat the proper amount of combustion air is inducted for all idleconditions. For example, a typical idle air bypass valve placed underthe control of the engine control computer may strive to maintain astable idle speed for the engine irrespective of the load imposed on theengine or of the engine temperature. For example, if the idle load onthe engine changes so that there is a resulting change in manifoldvacuum, the idle air bypass valve should respond by making acorresponding change in the degree of restriction that it imposes on theidle air flow such that proper air flow for the desired idle operationis maintained.

Heretofore, certain engine idle control strategies have involvedanticipatory adjustment of the idle air bypass valve prior to allowingchanges in accessory loadings of the engine (i.e., air conditioningload, power steering load, etc.). One object of the present invention isto provide an idle air bypass valve which exhibits a sufficiently fastresponse that becomes possible to eliminate such anticipatoryadjustments.

Certain known solenoid-actuated idle air bypass valves are mechanicallybiased to be normally closed and therefore require a certain degree ofelectrical energization before opening. If the electrical energizationis not received by the solenoid, or the solenoid actuator itself fails,opening of the idle air bypass is impossible, and typically the enginecannot be started. Another object of the present invention is to providean idle air bypass valve which is open at engine starting without theneed for electrical power to the valve. A related feature is that in theevent of electrical failure of the solenoid-actuator or of the controlcircuitry to the solenoid, the idle air bypass valve of the inventionstill permits the passage of some air into the engine so that it ispossible that the engine may remain running and therefore be driven to aservice facility.

The foregoing, along with additional features and benefits of theinvention, will be seen in the ensuing detailed description that isaccompanied by a drawing. The drawing discloses an exemplary presentlypreferred embodiment of the invention according to the best modecontemplated at the present time in carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a longitudinal cross-sectional view through an idle air bypassvalve assembly embodying the invention and shows the assembly inassociation with the main induction passage of a fuel injected engineand the engine electronic controller.

FIG. 2 is a longitudinal cross-sectional view through another embodimentof idle air bypass valve according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows an idle air bypass valve assembly 10 in association withthat portion of the main air induction passage 12 of a fuel-injected,spark-ignited automotive internal combustion engine which contains athrottle mechanism 14 shown in closed position. The arrows 16 representthe direction of combustion air flow into the engine when throttlemechanism 14 is opened to accelerate the engine from idle.

Valve assembly 10 comprises a body 18 having an inlet 20 and an outlet22. Inlet 20 is placed in fluid communication with induction passage 12at a point upstream of throttle mechanism 14 while outlet 22 is placedin fluid communication with induction passage 12 at a point downstreamof the throttle mechanism. The arrows 24 denote the idle air bypass flowthrough body 18 between inlet 20 and outlet 22.

The path of idle air bypass through body 18 contains a frustoconicalvalve seat 26 at the rim of a circular boss 28 that is fashionedintegrally with and internally of body 18. A generally tubularcylindrical-shaped valve pintle 30 is disposed in the path of idle airbypass through body 18 coaxially with valve seat 26 and is arranged forlongitudinal positioning along the coaxis. The drawing shows pintle 30fully unseated from valve seat 26, thereby rendering the idle air bypassfully open. Increasing the displacement of pintle 30 toward valve seat26 from the FIG. 1 position will increasingly restrict the bypass untilsuch time as full seating occurs thereby closing the bypass to flow. Thepintle is shaped in such a manner that a desired relationship betweenrestriction and pintle position is obtained. Pintle 30 further includesa depending stem 32 that aids in maintaining coaxiality of the pintlewith valve seat 26. For all positions of the pintle, stem 32 is guidedby a ring 34 fashioned integrally with and internally of body 18. Thering's opening is constructed in a toothed manner so that air can flowfreely through the ring when the pintle is unseated from the valve seat.

Pintle 30 still further includes a flange 36 at the end thereof that isopposite stem 32. The outer margin of flange 36 is joined in a sealedmanner with the inner margin of a flexible annular diaphragm 38. Theouter margin of diaphragm 38 is held in a sealed manner interiorly ofbody 18. More specifically, body 18 comprises multiple parts assembledtogether, with the entire outer margin of the diaphragm being capturedbetween mating portions of parts 40 and 42, and the latter two partsbeing held in assembly by a crimp ring 44.

Body 18 is shaped such that in cooperation with flange 36 and diaphragm38, two variable volume chambers 46 and 48 are formed interiorly of body18. Flange 36 and diaphragm 38 form a movable wall that is positionablegenerally in the axial direction to axially position pintle 30 withrespect to valve seat 26. The positioning of this movable wall iscontrolled by the respective volumes of the two variable volume chambers46, 48.

Chamber 48 forms a portion of the idle air passage; chamber 46, aportion of a flow path 50 that, at least in part, parallels the idle airpassage. In the illustrated valve assembly, this flow path 50 thatparallels the idle air passage begins at the distal end of stem 32 andextends completely through pintle 30. From there, it continues aschamber 46 and finally exits chamber 46 as a radial passage that isplaced in fluid communication with induction passage 12 in the samemanner as is outlet 22.

That portion of flow path 50 which extends through pintle 30 contains avalve element 52, a helical coil spring 54, and a valve seat 56. Aninternal shoulder 58 of the pintle within flow path 50 forms both a seatfor one end of spring 54 and an orifice 60 for flow path 50. Theopposite end of spring 54 bears against a shoulder of valve element 52to urge the valve element into contact with the semi-spherical distalend of a pin 62 that is a part of an actuating means 64 that will bedescribed in detail later on. The drawing illustrates valve element 52unseated from seat 56 so that the area circumscribed by seat 56 is opento flow. The O.D. of the valve element is sized in relation to thepassageway through the pintle such that air can flow freely past thevalve element when it is unseated from valve seat 56; however, when thevalve element is seated on the valve seat, flow into chamber 46 from theinlet of flow path 50 is not allowed. The valve seat 56 is a separatecircular annular part whose outer edge is joined in a sealed manner tothe pintle after valve element 52 and spring 54 have been assembled intothe pintle. The I.D. across valve seat 56 is sufficiently large inrelation to the diameter of the portion of pin 62 passing therethroughthat they impose no significant flow restriction in comparison to thatof orifice 60 for all but the least unseated positions of valve element52 from valve seat 56, such as that of FIG. 1.

A helical coil spring 66 is disposed within chamber 48 and functions tobias pintle 30 away from valve seat 26 such that the movable wall thatis formed by flange 36 and diaphragm 38 is urged into abutment againstthe interior of part 40. In such condition, chamber 48 has maximumvolume and chamber 46, minimum volume. Stops 68 that provide theabutment stop between the movable wall and part 40 are circumferentiallyspaced so that communication between radially inner and outer portionsof chamber 46 is not lost when the volume of chamber 46 is at itsminimum. A second orifice 70 is provided in flow path 50 and is locatedat the exit of the flow path from chamber 46.

The relative sizes of the orifices 60 and 70 are important incontrolling the flows into and out of chamber 46. Specifically, whenflow through flow path 50 is permitted, orifice 60 permits chamber 46 tobe filled at a faster rate than the chamber can be exhausted throughorifice 70. The effect is to urge chamber 46 toward maximum volume.

The description of actuating means 64 will now be given. The pin 62 is apart of a solenoid assembly 72 that is disposed within a cylindricalwalled portion 74 that is integrally formed with part 40. After assemblyof the solenoid assembly into body 18 through the open end of walledportion 74, said open end is closed in a sealed manner by a circular endclosure 76 and such that the solenoid assembly is constrained againstaxial displacement within walled portion 74. Part 40 has a suitable hole78 through which pin 62 passes before passing through the hole of valveseat 56.

Solenoid assembly 72 further comprises a bobbin 80 containing a woundelectromagnetic coil 82 between its end flanges. There are metal polepieces 84 and 86 at the bobbin's ends, and the exterior of the bobbin iswithin a metal shell 88 that extends between said pole pieces. Adjoiningpole piece 84 and extending part way into the circular central bore ofthe bobbin is a stator 90. A part 92, together with pin 62, form anarmature that is positionable along a portion of the bobbin's centralcircular bore in accordance with the degree of magnetic force that isexerted by the solenoid assembly when energized by electric current thatis delivered via terminals 94 to coil 82. Pin 62 and part 92 are joinedin any suitable manner for motion in unison, but it is desirable for thepin to be of a non-magnetic material so that it does not promote strayflux that might otherwise impair the solenoid's efficiency. Before theend of the assembly is closed by pole piece 84, pin 62 is passed, shankend first, through the bore of stator 90, and a helical coil spring 96is disposed between the pin's head and pole piece 84 for the purpose oftending to urge the pin's head against a shoulder within the statorbore. A sleeve 100 is fitted into the bore of the stator below shoulder98 to aid armature alignment.

As increasing electric current is delivered to coil 82, the armature isincreasingly retracted into the bobbin so that the axial positioning ofthe armature is a function of the energy input to the solenoid. Theenergy input to the solenoid is under the control of an electronicengine controller 102, and the solenoid may be energized with either acontrolled D.C. or pulse width modulated input.

Valve 10 operates in the following manner. Inlet 20 and the entrance endof flow path 50 are communicated to filtered air that is essentially atatmospheric pressure. Outlet 22 and the exit end of flow path 50 arecommunicated to the engine manifold. The drawing depicts the conditionof no manifold vacuum and no electrical energy input to the solenoidfrom engine controller -02. The idle air bypass is therefore fully opento flow.

The idle air bypass is sized such that upon starting and idle running ofthe engine, chamber 48 is placed at or near manifold vacuum. Chamber 46on the other hand remains communicated essentially to atmosphericpressure. Consequently, upon starting and idling of the engine (throttlemechanism 14 remaining closed), the pressure differential created acrossthe movable wall formed by diaphragm 38 and pintle flange 36, inconjunction with the force of spring 66 acting on the movable wall, aresuch as to cause the pintle to move toward closure of the bypass so longas there continues to be no electrical energy input to solenoid coil 82.The motion of the pintle toward valve seat 26 will however beaccompanied by a corresponding relative motion of valve element 52toward valve seat 56 due to the effect of spring 54. In the positiondepicted by FIG. 1, the amount of pintle travel that is required to seatthe pintle on valve seat 26 exceeds that at which valve element 52 seatson valve seat 56. In other words, valve element 52 will close flow path50 before pintle 30 can close the idle air bypass.

The closure of flow path 50 immediately stops the communication ofchamber 46 to atmosphere with the result that vacuum begins to beimmediately drawn in the chamber by virtue of the communication of thechamber to the engine intake manifold via orifice 70. Whereas chamber 46had been increasing in volume and chamber 48 decreasing in volume whilechamber 46 was communicated to atmosphere, this now reverses causing thepintle to move away from valve seat 26. A small amount of such motionhowever will re-unseat valve element 52 from seat 56 with the resultthat flow path 50 is re-opened to atmosphere through orifice 60. Sincethe latter is less restrictive than orifice 70, the vacuum in chamber 46immediately commences to diminish as the pressure in the chamber movestoward atmospheric.

The nature of the valve action is therefore seen to be a regulatory onewhereby the pintle is regulated in an essentially stable manner to causea certain degree of opening of the bypass that allows a suitable amountof idle air flow for a corresponding level of manifold vacuum so thatthe engine can continue to idle, even if the solenoid is neverenergized. It can therefore now be appreciated that the idle air bypassvalve of the present invention can avoid the loss of idle air flow intothe engine in the event of a condition corresponding to the loss ofelectrical power to the valve solenoid, such a condition occurringeither because of a failure of the solenoid or of the control circuitryfrom engine controller 102.

The electrical energization of solenoid assembly 72 will produce are-positioning of pin 62 from the position of FIG. 1 against the forceexerted by spring 96 as it is being compressed. The amount ofre-positioning is correlated with the degree to which the solenoidassembly is electrically energized. In other words, the greater thedegree of energization, the more that pin 62 is retracted into thesolenoid assembly. The effect of any particular amount of pin retractionis to cause a corresponding stable re-positioning of pintle 30, andhence a corresponding adjustment in the degree of restriction that isimposed on the idle air flow by the idle air bypass valve. Enginecontroller 102 operates on an idle control strategy that is determinedby the engine manufacturer and results in operation of the idle airbypass valve appropriate to that strategy.

The valve assembly is able to compensate for rapid changes in intakemanifold vacuum. If there is an increase or decrease in manifold vacuumat engine idle due to a change in engine load, the valve can react todecrease or increase the air flow as required. Such an automaticcompensation feature can keep engine idle speed stable and offers thepotential for eliminating the need for anticipatory adjustment of thevalve assembly before load changes are allowed to occur.

Detailed design of any specific valve assembly embodying principles ofthe invention is executed using conventional design and engineeringprocedures. Several of the parts, such as body 18, cap 76, and pintle 30for example, can be fabricated from suitable plastics.

FIG. 2 presents another embodiment 110 of idle air bypass valveassembly. Since many of the parts of embodiment 120 correspond with likeparts of the first embodiment 10, many of the same reference numerals inFIG. 1 will also be used in FIG. 2 to designate such corresponding partswithout necessarily including a detailed description thereof.

One difference that is immediately noticeable between the twoembodiments is that in FIG. 2 body 18 is arranged and constructed suchthat solenoid assembly 72 is disposed on the opposite side of the valveassembly from its location in the valve assembly of FIG. 1. A secondnoticeable difference is that pintle 30 and valve element 52 arearranged and constructed such that valve element 52 is exterior ofpintle 30 in FIG. 2 whereas in FIG. 1 the valve element is interior ofthe pintle. A third noticeable difference is the inclusion in FIG. 2 ofan internal part 122 that forms both a circular cylindrical sleeve 124for axially guiding pintle 30 and a wall 126 forming a physical boundarybetween chamber 48 and the idle air bypass flow through body 18 betweeninlet 20 and outlet 22.

Continuing with description of FIG. 2, pintle 30 has a constructionwherein its head 128 is disposed on a circular cylindrical tube 130. Asuitable way to fabricate the pintle is by constructing tube 130 frommetal and then insert-molding plastic onto the outside of the tube tocreate head 128. The inside diameter of diaphragm 38 joins with theoutside diameter of a circular disc 132. At its center the disc containsa circular hole through which tube 130 passes in a manner such that thedisc and tube are joined and sealed while the interior of the tube isplaced in communication with chamber 46. Spring 66 is disposed betweendisc 132 and a seat in wall 126 to bias head 128 against wall 126 andcause chamber 46 to assume a minimum volume. FIG. 2 portrays thiscondition.

Communication of chamber 46 with the intake manifold side of the mainair induction passage is established by placement of orifice 70 throughthe side wall of tube 130 such that the orifice faces outlet 22 for allpositions of pintle 30. FIG. 2 reveals that a suitable clearance isprovided in head 128 so that orifice 70 is unobstructed. Communicationof chamber 46 with the air intake side of the main air induction passageis established by placement of orifice 60 in the end wall of tube 130that is toward solenoid assembly 72.

Since valve element 52 is exterior of the pintle, it controls orifice 60directly. The construction of valve element 52 in FIG. 2 is somewhatdifferent from that of FIG. 1. In FIG. 2 the valve element is seen tocomprise a rubber button which is molded to the center of a perforateddisc 134. While spring 54 acts on disc 134 to bias valve element 52 awayfrom orifice 60 and against the distal end of pin 62, FIG. 2 portrays acondition where energization of solenoid assembly 72 is causing acertain extension of pin 62 from the fully retracted position.

One of the functional aspects of valve assembly 110 is that the vacuumin chamber 48 can be made less sensitive to certain pulsations that mayoccur in the manifold vacuum. This is accomplished by providing onlylimited communication through wall 126 between chamber 48 and the idleair bypass through the valve assembly. For this purpose a close, but notexcessively frictional, fit is provided between guide sleeve 124 andtube 130, and an orifice 138 is provided through wall 126. Accordingly,the construction dampens the effect on the diaphragm of any excessivevacuum or pressure surges that may occur in the idle air bypass. Thisfeature may be important in certain applications of the idle air bypassvalve assembly.

A further feature of valve assembly 120 is that a calibration adjustment140 is provided for setting pin 62 with respect to the armature part 92.

The functional relationships between the various parts of valve assembly120 are like those described for the corresponding parts of valveassembly 20 and in the interest of conciseness they need not beelaborated upon again. It should be mentioned that whereas FIG. 1portrays valve assembly 20 in a condition where the engine is notrunning and the solenoid is not energized, FIG. 2 portrays a conditionwhere the solenoid is energized and the engine is being started.

While a presently preferred embodiment of the invention has beenillustrated and described, it should be appreciated that principles areapplicable to other embodiments.

What is claimed is:
 1. In an internal combustion engine having a maininduction air passage through which combustion air is inducted when theengine is operating at non-idle, an electronic control system thatexercises control over certain functions associated with engineoperation, and an idle air bypass valve assembly comprising an idle airpassage bypassing that portion of the main induction air passage whichcontains a throttling mechanism for the main induction air passage, anidle air control valve for selectively controlling idle air flow throughsaid idle air passage, a mechanism for operating said idle air controlvalve comprising a transducer having an armature means that isselectively positionable along a path of travel in accordance with thevalue of a control signal issued by the electronic control system, theimprovement in said idle air bypass valve assembly which comprises amovable wall that separates two variable volume chambers from each otherand that is selectively positionable in accordance with the respectivevolumes of said variable volume chambers to select the degree ofrestriction imposed by said idle air control valve on flow through saididle air passage, one of said variable volume chambers being incommunication with said idle air passage at a location along said idleair passage that is between said idle air control valve and the engineside of said throttling mechanism, and the other of said variable volumechambers being in communication with said idle air passage at twolocations which are spaced apart along said idle air passage and each ofwhich comprises a corresponding orifice means, and a valve mechanismthat is operable by a means that includes said armature means toregulate flow through at least one of said orifice means, said other ofsaid two orifice means being smaller than said one orifice means.
 2. Theimprovement set forth in claim 1 wherein said one variable volumechamber is in communication with said idle air passage by means of afurther orifice means.
 3. In an internal combustion engine having a maininduction air passage through which combustion air is inducted when theengine is operating at non-idle, an electronic control system thatexercises control over certain functions associated with engineoperation, and an idle air bypass valve assembly comprising an idle airpassage bypassing that portion of the main induction air passage whichcontains a throttling mechanism for the main induction air passage, anidle air control valve for selectively controlling idle air flow throughsaid idle air passage, a mechanism comprising a transducer for operatingsaid idle air control valve in accordance with the value of a controlsignal issued by said electronic control system, the improvement in saidmechanism which comprises a movable wall that separates two variablevolume chambers and is positioned by the respective volumes of said twochambers, the positioning of said movable wall serving tocorrespondingly position said idle air control valve for selectivelycontrolling idle air flow through said idle air passage, one of saidchambers being in communication with said idle air passage at a locationalong said idle air passage that is between said idle air control valveand the engine side of said throttling mechanism, and the other of saidchambers being in communication with said idle air passage via orificemeans arranged and sized to allow air to enter said other chamber at arate that is different from the rate at which air can exit said otherchamber, and valve means operable by said transducer for regulating flowthrough said orifice means.
 4. The improvement set forth in claim 3wherein said orifice means comprises a pair of orifices which are spacedapart along said idle air passage, and said valve means acts directlywith only one of said pair of orifices.
 5. For use in an internalcombustion engine having a main induction air passage through whichcombustion air is inducted when the engine is operating at non-idle, anidle air bypass valve assembly comprising an idle air passage forbypassing a portion of the engine main induction air passage whichcontains a mechanism for throttling the engine main induction airpassage, an idle air control valve for selectively controlling idle airflow through said idle air passage, a mechanism for operating said idleair control valve comprising a transducer having an armature means thatis selectively positionable along a path of travel in accordance withthe value of a control signal received from an electronic control systemthat exercises control over certain functions associated with engineoperation, said idle air bypass valve assembly comprising a movable wallthat separates two variable volume chambers from each other and that isselectively positionable in accordance with the respective volumes ofsaid variable volume chambers to select the degree of restrictionimposed by said idle air control valve on flow through said idle airpassage, one of said variable volume chambers being in communicationwith said idle air passage via a first orifice means and the other ofsaid variable volume chambers being in communication with said idle airpassage via a second orifice means and a third orifice means thatcommunicate with said idle air passage at spaced apart locations alongsaid idle air passage, and a valve mechanism that is operable by a meansthat includes said armature means to regulate flow through said secondorifice means, said third orifice means being smaller than said secondorifice means.
 6. For use in an internal combustion engine having a maininduction air passage through which combustion air is inducted when theengine is operating at non-idle, an idle air bypass valve assemblycomprising an idle air passage bypassing a portion of the engine maininduction air passage containing a mechanism for throttling the enginemain induction air passage, an idle air control valve for selectivelycontrolling idle air flow through said idle air passage, a mechanismcomprising a transducer for operating said idle air control valve inaccordance with the value of a control signal issued by an electroniccontrol system that exercises control over certain functions associatedwith engine operation, said mechanism comprising a movable wall thatseparates two variable volume chambers and is positioned by therespective volumes of said two chambers, the positioning of said movablewall serving to correspondingly position said idle air control valve forselectively controlling idle air flow through said idle air passage,both of said chambers being in communication with said idle air passage,one via an orifice means arranged and sized to allow air to enter at arate that is different from the rate at which air can exit, and valvemeans operable by said transducer for regulating flow through saidorifice means.
 7. The improvement set forth in claim 6 wherein saidorifice means comprises a pair of orifices, one larger than the otherand wherein said valve means is disposed for acting directly on only oneof said pair of orifices.